ARCHIVED REPORTS_DRAFT ENVIRONMENTAL IMPACT REPORT

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INCREASED LAND DISPOSAL ALTERNATIVE The Increased Land Disposal Alternative would maximize the discharge of treated effluent to nearby agricultural lands. In order to maintain existing water quality and constituent loadings to the San Joaquin River from the time the WQCF reaches its current permitted capacity of 9.87 mgd ADWF through the proposed buildout capacity of 27 mgd ADWF, it is estimated that a maximum effluent-to-land disposal capacity of 18 mgd would be required. Treated effluent from the WQCF is currently either land applied to approximately 190 acres of City-owned land or discharged to the San Joaquin River. The City has examined a number of effluent-to-land disposal strategies that would have sufficient capacity for disposal of 18 mgd of treated wastewater year-round. Because of the relatively high unit cost and other implementation constraints of urban water reuse,the increased land disposal alternative would apply undisinfected, denitrified, secondary effluent to existing City-owned land surrounding the WQCF and to future City-purchased land at some distance from the WQCF. While the City has examined the costs of purchasing land from one to 10 miles away for effluent disposal, economic considerations and land availability make the purchase of land farther away from the WQCF a more tenable proposition. To that end,the increased land disposal alternative includes high-rate irrigation(260 in/yr)of City-owned land at the WQCF property(4,600 ac-ft/year or 4.11 mgd) and agricultural irrigation on acreage within 10 miles of the WQCF that would be purchased by the City(15,560 ac-ft/year or 13.89 mgd)as a means of collectively applying 18 mgd of undisinfected, denitrified, secondary effluent to land year-round. This alternative would allow the reclamation of up to approximately two thirds of WQCF effluent at the proposed build-out capacity of 27 mgd ADWF. Additional pipelines would be required to convey treated effluent from the WQCF to the selected land disposal site.All facilities proposed at the WQCF to treat up to 27 mgd of wastewater and proposed collection system and recycled water distribution pipelines would be constructed under this alternative. ADVANCED WASTEWATER TREATMENT ALTERNATIVE Because the proposed project includes nitrification-denitrification,tertiary filtration and UV disinfection facilities, the remaining advanced wastewater treatment options available to the City are microfiltration and reverse osmosis (MF/RO). RO is a membrane separation process that is used for the removal of dissolved constituents from wastewater remaining after advanced treatment with tertiary filtration or microfiltration. RO treatment relies on applied pressure to force water through a semi-permeable membrane while restraining the passage of particulate and high molecular weight constituents. Membranes exclude ions,but require high pressures to produce the deionized water. Passage of water through the membrane produces a relatively ion free effluent stream and a concentrated brine stream. MF occurs prior to RO in order to remove larger organic and inorganic particles that foul the RO membrane and thus increase membrane resistance to water flow and reduce membrane service life. The Advanced Wastewater Treatment alternative would involve the implementation of advanced microfiltration and reverse osmosis (MF/RO)technology. In order to maintain existing water quality and TDS loadings in the San Joaquin River from the time the WQCF reaches its current permitted capacity of 9.87 mgd ADWF through the proposed buildout capacity of 27 mgd ADWF, it is estimated that a maximum MF/RO capacity of 21 mgd would be required(LWA 2007). This alternative assumes that the blending of effluent streams of different qualities is permitted and,therefore,only a portion of WQCF tertiary effluent would need to undergo MF/RO prior to blending with non-MF/RO tertiary effluent and discharge to the San Joaquin River. Although no significant water quality impacts were identified for the project,the project would exceed currently adopted standards for aluminum(although a water effects ratio [WER] study has been completed to identify an appropriate site-specific objective for total aluminum in the San Joaquin River that is both sufficiently protective of aquatic life and identifies available assimilative capacity for aluminum in the river under which the WQCF can discharge its effluent); however,this impact was determined to be less than significant because the current adopted standard is believed,based on available science,to be overly protective of water quality and aquatic resources. The MF/RO process would reduce the concentration and loadings of aluminum and other metals in the effluent compared to the proposed project. This treatment technology is evaluated in the analysis provided below. Manteca WQCF and Collection System Master Plans EIR EDAW City of Manteca 2-3 Executive Summary